Prior art release agents for mitigating undesirable sticking of asphalt and concrete to these and other surfaces are well known. These release agents are commonly used to mitigate the sticking of such material to the surfaces of containers, mixers, forms and the like.
As those skilled in the art will appreciate, it is undesirable to have asphalt and concrete stick to such surfaces. When these materials stick to containers and mixers, it is often necessary to clean these items. Cleaning containers and mixers is typically a labor intensive task and is therefore generally time consuming and expensive.
Forms are used to define the shape of structures to be formed with concrete. For example, a wooden form may be used to define the shape of a roadway to be made by pouring concrete into the form. Once the material has cured somewhat, the form is typically removed. Of course, if the concrete sticks to the form, then it may be very difficult to remove the form from the structure.
Asphalt is commonly transported in the bed of a truck, such as for delivery from an asphalt plant to a job site. It is undesirable to have the asphalt stick to the truck bed.
Release agents are commonly applied to containers, mixers, truck beds and forms prior to pouring asphalt or concrete into them. Release agents are applied in numerous ways, including brushing, swabbing, or spraying, and upon application act as a physical barriers to mitigate adhesion of the asphalt or concrete to the relevant surfaces. This is somewhat analogous to the use of butter or shortening to mitigate the sticking of cake batter to a pan.
A commonly used release agent is diesel fuel. Diesel is inexpensive, readily available, and works reasonably well. It adheres fairly well to most surfaces, due to its high viscosity of around 68 (for no. 2D). Diesel is also relatively heavy, having a specific gravity of about 25 to 40 (with “Grade 1-D” around 40 and “Grade 2-D” around 35). Unfortunately, use of diesel fuel is unnecessarily polluting to the environment.
Some contemporary release agents comprise soybean oil in combination with various chemicals and additives. For example, it is known to use a mixture of 20%, by weight, or more of water in combination with soybean oil as a release agent. Various additives may be included to enhance emulsification of the water and soybean oil, encourage foaming, help the mixture spread when applied, make the mixture more visible, and/or provide a desired scent.
Although contemporary release agents have found widespread acceptance in the marketplace, such formulations suffer from inherent deficiencies. For example, a contemporary release agent comprising a mixture of soybean oil and water can generally only be used once. That is, a new application of such a contemporary release agent is generally required for each use. For example, each time a mixer or truck bed is filled with concrete or asphalt, or each time a wooden form is used for one of these materials, the release agent must typically be re-applied.
The re-application of a release agent for each use of a container, mixer, or form is undesirably costly. Not only must additional quantities of the release agent be used, but labor must be expended to perform the task of re-application.
Prior attempts to mitigate the deficiencies of such contemporary release agents include the use of permanent or semi-permanent anti-stick coatings, such as Teflon™ (a federally registered trademark of du Pont de Nemours and Company of Wilmington, Del.), as disclosed in U.S. Pat. No. 4,087,072, entitled FORM MEANS FOR FABRICATING PRE-CAST STRUCTURAL PANELS. However, in many applications the abrasive nature of asphalt and concrete makes the use of such permanent or semi-permanent coatings impractical. That is, the Teflon coating must be reapplied or the coated item must be discarded more frequently than is economically feasible.
In view of the foregoing, it is desirable to provide a more durable, yet economically feasible, release agent for mitigating undesirable sticking of asphalt, concrete, and the like to various surfaces.